The bus was carrying a group of high school students and their adult chaperones who had visited Harvard University. One person was hospitalized with life-threatening injuries and three with serious injuries. Thirty-five people were injured.

Authorities say the bus did not belong on the road, where a 10-foot height limit is in place and oversized vehicles are not authorized.

Ray Talmedge, owner of the Philadelphia-based Calvary Coach Bus company, told WCAU-TV that Jackson looked down at his GPS and saw the bridge too late.

Police say no charges have been filed. A phone number listed for Jackson rang unanswered Sunday.